Quentin Tarantino, as well as many others. Just because you go to film school doesn't mean you're ahead of everyone else. I've learned so much about film making, just from the internet and reading books in these past 4 months it's unbelievable. So I'm not planning on going to film school and spending 10,000+ dollars just to learn things I already know and can teach myself by experience.

It's very much possible, yes. Probably most of the people currently in filmmaking lack a degree, or at least don't use their degree. Mine is in multimedia systems, a field only tangentially connected to film and television.

That said:

Quentin Tarantino, as well as many others.

Very few others. Very, very few.

The poster boy for this used to be Robert Rodriguez, but there are certainly others. The problem is that the proportion of people who want to do what he did is very large, and the proportion who then manage to achieve it is vanishingly minute, but receive absolutely overwhelming amount of publicity. Now, I don't want to imply that there's anything wrong with either Tarantino or Rodriguez, but the prominence and visibility of these people enormously outweighs the availability of their career path. Simply put, a few - half a dozen, a dozen, whatever - people who managed to do this make a lot of people think they can too, but unfortunately, simple mathematics makes it all very improbable.

To put it yet another way, these people, particularly Rodriguez, were extremely lucky, and most successful people are willing to admit it. Meeting the right people at the right time can to an extent be controlled and planned, but achieving the sort of meteoric rise we're discussing here requires a sequence of coincidences (you have a project, someone needs a project of that sort, you happen to meet, etc.) that are simply very unlikely. The idea that determination and sincerity, not to mention competence, always and without exception wins out is inaccurate. Talented, persistent people fail all the time if they don't have at least a little luck.

In short, these people would not be well-known if the situation they are in were normal. It is a peculiarly American thing to believe that everyone can have conspicuous success, vast wealth, and endless happiness, and that everyone can and should pursue vanishingly small chances of achieving these things, but sadly it just doesn't happen very often.

Often, it's very much a matter of contacts and making the right connections. The right film schools help, as can going to some well known universities can help make these, or moving in the right circles.

I know this sounds crazy but are there any cases like that? Like people who go from homemade stuff and experience and fight their way up?

I went to film school. i learned more on an actual union set for a big budget movie, in four weeks, than i ever did in my four years as an undergrad, and 2 years as a masters student. experience trumps book study 1000 fold.

I thought Spielberg was always the greatest example of success without film school?

This from Wikipedia, and is very funny, USC admissions obviously blew it!

"After moving to California, he applied to attend the film school at University of Southern California School of Theater, Film and Television two separate times, but was unsuccessful."

Also James Cameron, creator of the two highest grossing movies of all time, no film school. But, he's Canadian, so he had a huge advantage from the get go

On the other end of the spectrum, it was really George Lucas that made USC, and film school in general, a viable path to success in this industry. It's not really the production training that has value, it's the network you establish.

You do not need a degree in a film related film to break into the industry. It couldn't hurt I'm sure, but a lot of "breaking in" is about who you know rather than what degree you have. My advice is network with other filmmakers. Offer to help them on their films. Build a resume you can use to shop around. No one is going to "hire" someone who has not film experience at all, especially for a role that requires you know basic things like camera loading (does anyone still do that). Even slating a production required that you know a process.